1. Field of the Invention
The present invention relates to an apparatus and a method for drive control, and computer product for mounting a predetermined medium onto a predetermined drive unit.
2. Description of the Related Art
Conventionally, a so-called tape library device that includes plural mediums, plural drive units, and a drive control apparatus receives an instruction from an upper unit, and mounts a predetermine medium onto a predetermined drive unit (see Japanese Patent Application Laid-open No. S58-108571).
Specifically, in reading data from or writing data to a medium stored in the tape library device, the upper device transmits, to the drive control apparatus, an instruction containing information of the specified medium and a specified drive unit onto which the medium is to be mounted. Upon receiving this instruction, the drive control apparatus confirms that the drive unit specified in the instruction from the upper unit is not being used. If the specified drive unit is not being used, the drive control apparatus transmits a signal to a robot to mount the specified medium onto the specified drive unit, based on the instruction from the upper unit.
On the other hand, if the specified drive unit is being used, the drive control apparatus replies to the upper unit that the drive unit is being used. Upon receiving this reply, the upper unit selects any other drive unit, different from the drive unit specified in the preceding instruction, and transmits an instruction containing information similar to the above, to the drive control apparatus. This information exchange between the upper unit and the drive control apparatus is repeatedly carried out until the specified medium is mounted onto the specified drive unit.
The media stored in the tape library device include media in which encrypted data are stored, and media in which unencrypted data are stored. The drive unit as one of the units that configure the tape library device includes drive units for encrypted data corresponding to the media in which the encrypted data are stored, and drive units for encrypted data corresponding to the media in which the unencrypted data are stored.
While configuring a tape library device to including both types of the drive units, the following problem occurs. That is, the drive control apparatus mounts the medium storing encrypted data onto the drive unit for unencrypted data, or mounts the medium storing unencrypted data onto the drive unit for encrypted data. This problem occurs because the drive control apparatus faithfully executes the instruction from the upper unit.
Therefore, at present, there is no other means to configure physically-different tape libraries, i.e., a tape library in which only drive units for encrypted data are present, and a tape library in which only drive units for unencrypted data are present. Consequently, configuring physically-different tape libraries has a problem in that cost performance and compactness of peripheral units of a computer cannot be achieved.